The present invention relates to improvements in an end milling tool adapted to cut workpieces through movement in its axial direction and to also effect sidewise cutting at right angles to the axis.
End mills of this type have a long main cutting end edge and a short auxiliary cutting end edge formed at the forward end of the mill so as to extend radially thereof and are also provided with outer axially extending peripheral cutting edges. The main and auxiliary cutting end edges drill or cut a workpiece in the direction of the axis of the mill, while the outer peripheral edges cut the workpiece sidewise, for example, to cut a side face thereof or form a groove therein. Since the main and auxiliary cutting end edges of the conventional end mills are positioned at the same axial location on the mill, such end edges are subjected to equal load when cutting in the axial direction. This gives rise to the problem that the short auxiliary cutting edge is liable to break or chip.
An object of the present invention is to reduce the cutting resistance to which the auxiliary cutting end edge is to be subjected to prevent the cutting edge from chipping or breaking.
Another object of the invention is to provide an end mill which is capable of smoothly cutting soft materials as well as hard materials.
Another object of the invention is to provide a drill having an increased life.
Other objects and features of the invention will become apparent from the following description with reference to the accompanying drawings, in which: